Security in Review after Man Wanders onto Chicago Airfield

Aviation officials are trying to learn how an allegedly intoxicated man was able to walk through a security gate and onto the airfield at Midway Airport, an official said Wednesday.

The incident prompted a brief shutdown of part of the airfield Sunday, forcing one arriving plane to circle around until it was reopened, Chicago Department of Aviation spokeswoman Wendy Abrams said.

The man apparently entered a service gate, possibly at the same time a vehicle was entering, Abrams said. He was spotted standing between two runways and was arrested.

Abrams said an FBI investigation determined that "this was likely an isolated event and this individual posed no major security threat." An FBI spokesman in Chicago did not immediately return a call seeking comment Wednesday.